In existing implementations for weighing of mail items in a stream, the means for transporting the article through the scale, such as a conveyor system, is made part of the scale platform. This increases the tare weight of the scale, resulting in increased settling time, which is the time between the full weight of the article being supported on the scale and the output of the scale becoming steady enough to make accurate weight measurements. Thus the addition of a scale has tended to slow down the throughput of a complete mail-handling system.
Present mail handling systems that incorporate a mail piece weighing apparatus include transport devices as part of the scale platform, or located atop the scale platform. These prior systems also stop each mail piece as it is being weighed, or slow down the speed of the mail piece significantly during the weighing process. For example, Clark, Jr. et al. U.S. Pat. No. 4,756,520 discloses a scale having a transport cage and envelope transport mechanism supported directly upon the scale. The mail piece transport system is not separate from the scale, and the envelopes are stopped in the weighing transport apparatus. Likewise, Miller et al. U.S. Pat. No. 6,759,602 discloses, in FIG. 2, a pair of mail piece weighing load cells forming part of the envelop transport platform. There is no teaching in the Miller patent of the advantages to be gained by separating the scale and transport mechanisms in a mail handling system, as in the present invention.